- In 2019 I had a swarm enter one of my empty hives only to abscond leaving behind a dozen bees that would not fly even when prodded. Two of these bees showed K-wing condition, where the two wings on one side of the thorax have become unattached.

- Examining the two hives I lost this Spring I found honey stores, few dead bees, and the queen with only a handful of workers.

- This Summer inspection showed my hives lacked sufficient capped honey for the winter (I had not harvested), so for the first time in the six years of beekeeping I fed 2:1 syrup until the end of September.

 

Although there may have been other factors involved, in my research on Trachea mites the above occurrences are indicative of trachea mite infestation. The diameter of the honey bee trachea is similar to a human hair. Trachea mites being microscopic makes it difficult for beekeepers to monitor mite levels and determine when to treat. All stages, males and females, larvae, and eggs are found in the bee’s respiratory system. The mites can infest the queen and drones, but the infestation of workers is what really impacts the colony.

 

In the early 1980’s Trachea mites invaded colonies in Mexico and by 1984 they were discovered in Texas. Although quarantines were put in place and infested hives were destroyed (43,000) the mites spread and were very lethal in thefirst year of contact, up to 100%. In the second year of exposure loss was 50%, and 25% the third year. Stocks of bees that were susceptible simply died out. In 1987 Varroa mites arrived in the U.S. adding to bee mortality.

 

The life cycle of the mite starts with a mated female leaving the trachea of her host, climbing to the tip of a setae {hair) and makes a transfer to a new host who are generally less than three days old. She is attracted to the first thoracic spiracle which expires air and she generally ignores the second and third spiracles which are used for intake of air. Entering the trachea, she will lay 8-10 eggs, producing one generation of mites per host. Her daughters may create a second generation if in longer living bees (winter bees). Development from egg to adult takes 11-12 days for males, 14- 15 days for females. To feed the mites pierces the trachea wall and consume the bee’s hemolymph. This feeding activity is believed to affect the surrounding flight muscles and/or hypopharyngeal glands. The scarring of the trachea and air flow reduction due to high mite density may also restrict the bee’s oxygen uptake.

 

Chemical control of the mites is challenging since the mites spend most of their life inside the bee. Fumigation using menthol was used in the early years. The current recommendation of the Honey Bee Health Coalition is fumigation with formic acid, in 65% liquid form or with commercially available Mite Away Quick Strips.

 

Non-chemical cultural controls designed to interfere with the mite’s life cycle can be helpful. Since the mites like to infest younger bees and older bees have a higher density of mites, management practices that reduce the level of old bees reduce the level of mites. Dividing colonies, done during mid-day, leaves behind older infested bees that are out foraging. By stocking divisions with emerging brood the percentage of young un-infested bees can be increased. Suppling the new divisions with new young queens also produces a high output of new bees free of mites. And finally using practices that reduce drifting of bees, both worker and drones, can help reduce the introduction of mites to the colony.

 

Another non-chemical treatment that has been found to be effective is the use of “grease patties”, made from a mixture of sugar and solid vegetable shortening. It is believed the bees, in feeding on the patties get coated with shortening that restricts the mites from transferring to new hosts. There are many recipes available, usually consisting of 2-3 parts granulated sugar to 1 part solid vegetable shortening. Recipes may also contain attractants like honey and lemon grass oil to encourage locating and feeding, or mineral supplements for added health benefit. With mite levels usually highest in the fall and winter, placing patties within easy access to the bees during this time may aide in controlling mites given the bees consume the patties. For my colonies I’m placing patties on 1/2” hardware cloth racks, contained in shallow tin foil pans, at the top of my Langstroth hives and the floors of my top-bar hives with plans to remove them in the spring. The wire racks allow the bees access both sides of the patty and the foil pan is insurance if temperature melts the patty.

 

The final area of control is to select or obtain stock resistant bees. Both Russian and Buckfast stock have shown high resistance to Trachea mites. And for breeding programs, it is best not to use queens that show low resistance.

 

Sources and additional information:

Honey Bees and Beekeeping: A Year in the Life of an Apiary. 3rd Edition. 2006. University of Georgia and Keith S. Delaplane

This site links to a video on the microscopic exam for Trachea mites. https://catalog.extension.oregonstate.edu/em9145 https://www.ars.usda.gov/southeast-area/baton-rouge-la/honeybeelab/docs/tracheal-mites-resistant-bees/ https://bee-health.extension.org/honey-bee-tracheal-mites-gone-but-not-for-good/